Key parameters at a glance
- A radius of 2.77 Earth radii
- A mass of 8.10 Earth masses
- Surface gravity around 1.06 g
- An orbital period of 30.133 days
- Semi-major axis 0.1820 AU
- Equilibrium temperature 536 K (263 °C)
- Distance from Earth 3,015.72 light-years
- Earth Similarity Index 0.448
- Travel time at Voyager 1 speed 53,182,218 years
3 siblings around Kepler-251
Kepler-251 d shares its host star with 3 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| Kepler-251 b | Super-Earth | 1.33 | 2.33 | 4.791 | 990 | 2014 |
| Kepler-251 c | Sub-Neptune | 2.77 | 8.10 | 16.514 | 655 | 2014 |
| Kepler-251 d this | Sub-Neptune | 2.77 | 8.10 | 30.133 | 536 | 2014 |
| Kepler-251 e | Sub-Neptune | 2.77 | 8.10 | 99.640 | 360 | 2014 |
Kepler-251 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#780of 1978
top 39.4%
This planet
2.77R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-251 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.77 | 11.21 |
| Mass (M⊕) | 1.00 | 8.10 | 317.83 |
| Density (g/cm³) | 5.51 | 2.09 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.06 | 2.53 |
| Insolation (S⊕) | 1.00 | 17.48 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 272489533
Gaia DR2
Gaia DR2 2078832551450444032
Gaia DR3
Gaia DR3 2078832551450444032
System
Kepler-251
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 30.13 Earth days (8.2% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1820 AU.
Transit Fingerprint
Depth
0.102 %
Duration
4.919 h
Impact parameter b
0.300
Rp / R★
0.032100
Transit midpoint (BJD)
2,455,023.3832
Photometric dip
Transit produces a flux drop of 1,016 ppm lasting ≈ 4.92 h.
Extended Orbital Architecture
Planet / star radius ratio
0.032100
Semi-major axis / stellar radius
28.500
Impact parameter (b)
0.300
Transit mid-time (BJD)
2,455,023.3832
Angular separation (arcsec)
0.19700
Eq. Temperature
536K
(263 °C)
Insolation (S⊕)
17.48
Earth = 1.00
Earth Similarity (ESI)
0.448
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Rowe et al. 2014Instrument
Kepler CCD Array
Publication
2014-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
Host System: Kepler-251
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,526 K — cooler than the Sun (5,778 K)
Estimated Age
2.00 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.890 R☉
Stellar Mass
0.891 M☉
Metallicity [Fe/H]
-0.06
Extended Stellar Properties
Surface gravity (log g)
4.486 dex
Stellar density
1.610 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
1.054 mas
Total Proper Motion
13.968 mas/yr
PM Right Ascension
-3.18 mas/yr
PM Declination
-13.60 mas/yr
Galactic Cartesian (pc)
x = 0.321 · y = -0.642 · z = 0.696
Equatorial (J2000)
RA 296.56622° · Dec 44.10581°
Galactic ℓ, b
77.907° · 9.551°
Ecliptic λ, β
315.786° · 63.383°
HTM-20 index
-1274721983
Similar Worlds
Kepler-1077 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.77 R⊕ · 3,592.3 ly
K2-75 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.77 R⊕ · 1,832.8 ly
Kepler-251 e
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.77 R⊕ · 3,015.7 ly
Kepler-251 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.77 R⊕ · 3,015.7 ly
Kepler-487 d
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.78 R⊕ · 2,845.2 ly
Kepler-449 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.76 R⊕ · 789.1 ly